If pyroclastic clouds from volcanoes can reach between 250 and 1000 ºC of temperature, and DNA suffers complete degradation at 190 ºC [1], I wonder how they managed to find anything to analyze here.
I wonder also how they discard the possibility of a later contamination.
I'm sure the analysts, the archeologists, and all the others who spent years of their life getting the education to do the analysis and doing the study, never considered this once at all and you're right it was just all solved by a simple internet comment with two minutes of thought and a single link from Google.
This seems to be a common thought pattern on this site and it might actually be interesting to see if there has ever been a case of some person solving hard problems outside of their field with a simple Google search.
Edit: Seems like this accounts only reason for existence is to throw doubt on everything after looking at their previous posts
Given the replication crisis in science, it seems like a lot of scientists are willing to overlook even obvious things as long as they get a paper published.
I would imagine that people that got trapped in buildings would have their DNA never reach anywhere near that temperature. In this case it seems like they got the DNA from plaster casts. I could see the very insides of the body not getting above 190.
If the interior of an oven can reach 200–250°C, and water suffers complete evaporation at 100°C, I wonder how pizza does not come out of the oven completely dehydrated.
> I wonder how pizza does not come out of the oven completely dehydrated
Is because water is trapped inside the pizza materials.
DNA and water are very different substances. One is very fragile, the other is practically indestructible
If the temperature changes, water just will change temporarily its state to became ice or vapor, and if that gas is contained, it will return to liquid as soon as the temperature allows it, as many times as needed. When the pizza is out of the oven, the water returns.
DNA can't do this out of a live cell.
DNA chains unzip and split away at 96ºC and then you need a live cell to recreate the molecule again. Lets assume that somebody ordered a pizza in the same year that Pompeii fell, as we know that half of DNA will vanish each 500 years (more or less), today more than 90% of all DNA in the pizza would be lost just by natural degradation. Now put this pizza in the oven at 200ºC and basically most if not all of this survivor DNA will be reduced to ashes.
But they are here talking about not just finding DNA, but also about knowing if was a man or a woman, That's even more impressive. Those tiny fragments of DNA survivor should belong also to identifiable parts of the X and Y chromosomes.
In this terms, finding "Y" means man, but not finding it does not mean woman. It means either woman or a man where all the short Y chromosome was included in the 99,99% of the DNA lost just by chance in the taken sample. This means that some of the identified girls could be really boys.
Evaporation cools the interiorvfor quite a while and the pyroclastic stream is just one trainload of heat and death for maybe half an hour. So the marrow aint cooked, its fresh and all the bacteria is denatured, the environment is a ashy cement tomb, so all liquid evaporating from the dna shards is take up by the surrounding ash-cement capsule. Not an expert ,just an enthusiastic guesser.
There are a couple of ways to rule out modern contamination.
Ancient DNA has certain characteristic damage that changes the sequence slightly, and you can use that to filter out any DNA that doesn't have that signature. Plus, you can maintain DNA profiles of all people involved in handling to ensure it's not modern contamination from the field workers or lab techs.
There are no historical accounts of people leaving Pompeii as a precaution, and no reason to believe an eruption was expected by anyone. Take for instance this letter from Pliny the Younger to Cornelius Tacitus [0], who provides the only written accounts of the eruption. Pliny witnessed the eruption from Misenum, on the other side of Vesuvius from Pompeii across the Bay of Naples. He mentions how tremors were not considered a cause for concern, and he only describes panicked fleeing as the eruption itself is taking place. By the way, the uncle he mentions is Pliny the Elder, who was in charge of the Roman Fleet in the area and who died attempting to rescue a friend of his from Stabiae, another town which was destroyed by the eruption but not quite as fulminantly as Pompeii.
My uncle having left us, I spent such time as was left on my studies (it was on their account indeed that I had stopped behind), till it was time for my bath. After which I went to supper, and then fell into a short and uneasy sleep. There had been noticed for many days before a trembling of the earth, which did not alarm us much, as this is quite an ordinary occurrence in Campania; but it was so particularly violent that night that it not only shook but actually overturned, as it would seem, everything about us. My mother rushed into my chamber, where she found me rising, in order to awaken her. We sat down in the open court of the house, which occupied a small space between the buildings and the sea. As I was at that time but eighteen years of age, I know not whether I should call my behaviour, in this dangerous juncture, courage or folly; but I took up Livy, and amused myself with turning over that author, and even making extracts from him, as if I had been perfectly at my leisure. Just then, a friend of my uncle's, who had lately come to him from Spain, joined us, and observing me sitting by my mother with a book in my hand, reproved her for her calmness, and me at the same time for my careless security: nevertheless I went on with my author. Though it was now morning, the light was still exceedingly faint and doubtful; the buildings all around us tottered, and though we stood upon open ground, yet as the place was narrow and confined, there was no remaining without imminent danger: we therefore resolved to quit the town. A panic-stricken crowd followed us, and (as to a mind distracted with terror every suggestion seems more prudent than its own) pressed on us in dense array to drive us forward as we came out. Being at a convenient distance from the houses, we stood still, in the midst of a most dangerous and dreadful scene. The chariots, which we had ordered to be drawn out, were so agitated backwards and forwards, though upon the most level ground, that we could not keep them steady, even by supporting them with large stones. The sea seemed to roll back upon itself, and to be driven from its banks by the convulsive motion of the earth; it is certain at least the shore was considerably enlarged, and several sea animals were left upon it. On the other side, a black and dreadful cloud, broken with rapid, zigzag flashes, revealed behind it variously shaped masses of flame: these last were like sheet-lightning, but much larger. Upon this our Spanish friend, whom I mentioned above, addressing himself to my mother and me with great energy and urgency: "If your brother," he said, "if your uncle be safe, he certainly wishes you may be so too; but if he perished, it was his desire, no doubt, that you might both survive him: why therefore do you delay your escape a moment?" We could never think of our own safety, we said, while we were uncertain of his.
> and no reason to believe an eruption was expected by anyone
Well it the hypothesis is that it lasted ~18 hours and that most people managed to leave during the early stages. After all if we base it only the number of bodies found Pompeii was pretty much abandoned by the end..
Herculaneum is smaller and less known, but only half an hour away and even better preserved. With proper planning you can visit both sites on the same day.
The first time I visited a tour guide screamed at some teenagers doing TikTok dances in the middle of the road and the second time I saw a tour guide scold a woman letting her kid play in one of the functioning water fountains.
Good for those tour guides, it sounds like they really respect their town and don't want it to degrade into generic tourist slop. It's good to have standards of decorum and behavior and to enforce them.
If pyroclastic clouds from volcanoes can reach between 250 and 1000 ºC of temperature, and DNA suffers complete degradation at 190 ºC [1], I wonder how they managed to find anything to analyze here.
I wonder also how they discard the possibility of a later contamination.
[1] https://www.researchgate.net/publication/236457118_Thermal_d...
I'm sure the analysts, the archeologists, and all the others who spent years of their life getting the education to do the analysis and doing the study, never considered this once at all and you're right it was just all solved by a simple internet comment with two minutes of thought and a single link from Google.
This seems to be a common thought pattern on this site and it might actually be interesting to see if there has ever been a case of some person solving hard problems outside of their field with a simple Google search.
Edit: Seems like this accounts only reason for existence is to throw doubt on everything after looking at their previous posts
Given the replication crisis in science, it seems like a lot of scientists are willing to overlook even obvious things as long as they get a paper published.
So, I think these are questions worth asking.
[dead]
I would imagine that people that got trapped in buildings would have their DNA never reach anywhere near that temperature. In this case it seems like they got the DNA from plaster casts. I could see the very insides of the body not getting above 190.
If the interior of an oven can reach 200–250°C, and water suffers complete evaporation at 100°C, I wonder how pizza does not come out of the oven completely dehydrated.
> I wonder how pizza does not come out of the oven completely dehydrated
Is because water is trapped inside the pizza materials.
DNA and water are very different substances. One is very fragile, the other is practically indestructible
If the temperature changes, water just will change temporarily its state to became ice or vapor, and if that gas is contained, it will return to liquid as soon as the temperature allows it, as many times as needed. When the pizza is out of the oven, the water returns.
DNA can't do this out of a live cell.
DNA chains unzip and split away at 96ºC and then you need a live cell to recreate the molecule again. Lets assume that somebody ordered a pizza in the same year that Pompeii fell, as we know that half of DNA will vanish each 500 years (more or less), today more than 90% of all DNA in the pizza would be lost just by natural degradation. Now put this pizza in the oven at 200ºC and basically most if not all of this survivor DNA will be reduced to ashes.
But they are here talking about not just finding DNA, but also about knowing if was a man or a woman, That's even more impressive. Those tiny fragments of DNA survivor should belong also to identifiable parts of the X and Y chromosomes.
In this terms, finding "Y" means man, but not finding it does not mean woman. It means either woman or a man where all the short Y chromosome was included in the 99,99% of the DNA lost just by chance in the taken sample. This means that some of the identified girls could be really boys.
dna gets destroyed, dnatured all the time. its just sugarcotton with extra ingredients .
Evaporation cools the interiorvfor quite a while and the pyroclastic stream is just one trainload of heat and death for maybe half an hour. So the marrow aint cooked, its fresh and all the bacteria is denatured, the environment is a ashy cement tomb, so all liquid evaporating from the dna shards is take up by the surrounding ash-cement capsule. Not an expert ,just an enthusiastic guesser.
[dead]
This is my question as well. How do they know that these DNA samples are not of the people who prepared and/or maintained the casts?
There are a couple of ways to rule out modern contamination.
Ancient DNA has certain characteristic damage that changes the sequence slightly, and you can use that to filter out any DNA that doesn't have that signature. Plus, you can maintain DNA profiles of all people involved in handling to ensure it's not modern contamination from the field workers or lab techs.
These makes sense.
Thanks for clarifying.
3 people downvoted me for the honest question.
In ancient times, Pompeii was a lot closer to the seashore and had at least one port, possibly two (the other on the Sarno river).
Port cities tend to have highly diverse populations.
The Romans also imported a massive amount of slaves from all over the Mediterranean into Italy over the several preceding centuries.
I bet the people who were left behind were mostly servants and laborers.
Because Vesuvio had been rumbling for days, most people with the means to do so had probably already left the city.
There are no historical accounts of people leaving Pompeii as a precaution, and no reason to believe an eruption was expected by anyone. Take for instance this letter from Pliny the Younger to Cornelius Tacitus [0], who provides the only written accounts of the eruption. Pliny witnessed the eruption from Misenum, on the other side of Vesuvius from Pompeii across the Bay of Naples. He mentions how tremors were not considered a cause for concern, and he only describes panicked fleeing as the eruption itself is taking place. By the way, the uncle he mentions is Pliny the Elder, who was in charge of the Roman Fleet in the area and who died attempting to rescue a friend of his from Stabiae, another town which was destroyed by the eruption but not quite as fulminantly as Pompeii.
[0] https://gutenberg.org/files/2811/2811-h/2811-h.htm#link2H_4_...Very cool stuff.
But why was he even there with a fleet? How did a fleet have time to sail there to witness the eruption?
Clearly there was cause for concern, even if written sources don't mention it.
And of course the final detail is the number of bodies found, much lower than the number of expected inhabitants.
Many houses were being remodeled from previous tremors, the owners probably long gone and left the laborers to their fate.
> and no reason to believe an eruption was expected by anyone
Well it the hypothesis is that it lasted ~18 hours and that most people managed to leave during the early stages. After all if we base it only the number of bodies found Pompeii was pretty much abandoned by the end..
Damn, I've never seen plaster casts of the Pompeii victims before. Equal parts fascinating and disturbing.
You should go to pompeii is incredible how preserved some of the city is
Herculaneum is smaller and less known, but only half an hour away and even better preserved. With proper planning you can visit both sites on the same day.
The first time I visited a tour guide screamed at some teenagers doing TikTok dances in the middle of the road and the second time I saw a tour guide scold a woman letting her kid play in one of the functioning water fountains.
Good for those tour guides, it sounds like they really respect their town and don't want it to degrade into generic tourist slop. It's good to have standards of decorum and behavior and to enforce them.
Good on those tour guides imo.
Sounds like some tourists don't understand the concept of respect
Also the only place I've been where you can see archeologists at work enthusiastically uncovering new artifacts right in front of you.
If you go to Pompeii the keyword on google maps is “Fugitives” had a hard time finding them on such a archeological site.